Apparatus for spraying materials in a prilling process



E. A. ROSS June 6, 1967 APPARATUS FOR SPRAYING MATERIALS IN A PRILLINGPROCESS Filed June 17, 1965 INVENTOR. EUGENE ALBERT ATTORNEY UnitedStates Patent APPARATUS FOR SPRAYING MATERIALS IN A PRILLIN G PROCESSEugene Albert Ross, Littleton, Colo., assignor, by mesne assignments, toChicago Bridge & Iron Company, Oak Brook, Ill., a corporation ofIllinois Filed June 17, 1965, Ser. No. 464,725 6 Claims. (Cl. 18-2.7)

This invention relates to apparatus for spraying material in a prillingprocess, particularly apparatus capable of spraying a great variety ofnon-viscous, viscous and sticky materials to form uniform, sphericaldroplets.

The main object of the invention is to provide apparatus for sprayingmolten material in such manner that it will remain molten and break upinto spherical, uniform droplets before leaving the confines of theapparatus.

Another object is to provide apparatus constructed so as to prevent themolten material from bridging across the face of the nozzle or nozzleswhich causes thickened streams and oversize droplets to be formed.

Another object is to provide spray orifices of novel construction andmeans for uniformly heating the orifices to thereby maintain the liquidstreams passing therethrough in a molten state until they have time tobreak up completely into spherical droplets without stringing ordistortion of the droplets.

Equipment heretofore used for prilling tower operation includesperforated plates, hollow cone or full cone pressure nozzles, andperforated rotating devices which utilize centrifugal force to spraymaterial. These devices perform the basic function of breaking up themolten material into droplets but they are limited with respect to thematerials which they can handle and the uniformity of droplets produced.The perforated plates produce the most uniform droplets but arediflicult to keep Warm. They plug easily and are subject to bridging ofthe material streams across the fiat bottom surface of the plate.

The quality and uniformity of droplets produced from both the cone typepressure nozzles and rotating devices is very poor. These types of sprayequipment also require large spray areas which limit their use to verylarge prilling towers.

All three prior art types of nozzles are unable to prill viscous andsticky materials because of plugging, deformation of the droplets, orstringing, which occurs when the material emerges from the sprayingmechanism and is cooled before the .sprayed melt has time to break upinto droplets.

The spray apparatus described herein overcomes the objections to priorart equipment and efiiciently sprays many molten materials, no matterhow adhesive or sticky, with a minimum of plugging, and in such mannerthat the materials will break up into uniform, spherical droplets ofideal size for cooling in a prilling tower. There are thousands ofmaterials which can be sprayed. Examples are fatty acids, wax polymers,pentachlorphenol, fatty alcohols, wood resins, sulphur, pitch,nitrolime, nitrophosphate, amides and glycols. Materials which may betreated successfully by the herein described apparatus have viscositiesranging from to 3000 centipoises and melting points within the range of120 F. to 1000 F.

The following are examples of materials which differ greatly inviscosity and melting temperatures:

In the drawings:

FIG. 1 is a vertical sectional view, partly in elevation, of apparatusembodying my invention for spraying material in a prilling process.

FIG. 2 is a top plan view of a nozzle which is part of the apparatus.

FIG. 3 is a vertical sectional view in the plane of the line 33 of FIG.2.

FIG. 4 is an elevational view on an enlarged scale of one of the orificeinserts of the nozzle.

In the embodiment of the invention shown in the drawings, a container 10supplies molten material through conduits 11, 12, to nozzles indicatedas a whole at 13. Valves 14 located in the conduits 12 control the flow.The container 10 is a conditioning tank where the material to be sprayedis adjusted to the optimum temperature and pressure for best sprayingresults.

Spray nozzles 13 each consist of a cylindrical pressure chamber 15provided with a quickly removable top 16 secured to the flange 17 onwall 18 by bolts 19 and nuts 20. The bottom 21 of each nozzle is drilledand tapped to provide threaded openings for any desired number ofspecially designed orifice inserts 22.

The inserts 22 are provided with a screw threaded member 23 for engagingthe openings: in the bottom 21 of the nozzle 13. The body portion 24 hasa thin walled tube 25 depending from its lower end. The passageway 26communicates with the hollow interior 40 of the threaded portion 23 andwith the nozzle chamber 15 at its upper end. The hollow interior 40 isshown in FIG. 4 as an enlarged part of the passageway extending from theend of the insert which attaches to the nozzle and terminating beforethe passageway enters the thin walled tubulaI member at the other end ofthe body. Its lower end 27 is an orifice in the tube 25 which deliversmolten materials into a hot chamber 30 having a top 28 in which thenozzles are mounted.

Orifice sizes may vary from 0.025" to 0.125" diameter. As examples, theorifice size for spraying myristyl alcohol preferably is .029"; for coaltar resin .035"; for caustic soda .035"; wax plastic .040"; hydrocarbonresin .040; and coal tar pitch .052 diameter.

The hot chamber '30 is about three feet in height and of suflicientwidth to accommodate any desired number of nozzles 13. The chamberprovides space for the outlets of the orifice inserts 22 and a heatedarea where the streams leaving the orifices 27 at the ends of the tubes25 of the inserts 22 have suflicient time to break up and form dropletsbefore being exposed to any cooling medium, and to uniformly heat theorifices in the bottoms of the spray nozzles to prevent plugging andother obstacles to efficient formation of uniform droplets.

The chamber 30 may be constructed and heated in a variety of Ways, suchas by electrically heated elements Material Melt. Temp., Hot Chamber FTemperature, F.

Myristyl Alcohol 120 120 Hydrocarbon resin 250 300 Wax Plastic 300 350Coal Tar Pitch. 400 450 Coal Tar Resin 575 600 Caustic Soda 640 650 Thehot chamber 30 maintains viscous, high temperature, and sticky materialsat proper temperatures to form uniform, spherical droplets beforeleaving the chamber. This is an achievement not heretofore possible withprior art spraying devices.

Below the chamber 30 is a conventional prilling tower 33 broken away, inwhich the droplets cool and drop to receiving means known in theprilling art.

Changes may be made in details of construction and arrangement of partswithout departing from the scope of the invention defined by theappended claims.

I claim:

1. A nozzle having walls surrounding a pressure chamber with a pluralityof apertures in the bottom wall, and

removable orifice inserts in the apertures,

said orifices comprising a body having an orifice passageway extendinglongitudinally therethrough, a depending thin walled tubular member atone end of the body through which the passageway runs axially, and meanson the other end of the body to attach the orifice insert to theaperture.

2. A nozzle according to claim 1 in which the orifice passageways rangein diameter from 0.025 inch to 0.125 inch.

3. Apparatus for spraying material in a prilling process comprising:

a nozzle having walls surrounding a pressure chamber with apertures inthe bottom wall,

removable orifice inserts in the apertures, the orifice insertscomprising a body having an orifice passageway extending longitudinallytherethrough, a depending thin walled tubular member at one end of thebody through which the passageway runs axially, and means on the otherend of the body to attach the orifice insertto the aperture,

a hot chamber housing defining a hot chamber,

said nozzle being mounted at the top of the hot chamber for sprayingliquid material through the orifice inserts directly into the hotchamber, and heating means placed about the hot chamber to pro vide heatto the hot chamber to keep the tempera ture of the sprayed material frombeing lowered until after it breaks up and forms droplets or prills. 4.Apparatus for spraying material in a prilling process 'comprising:

a nozzle having walls surrounding a pressure chamher with apertures inthe bottom wall,

- removable orifice inserts in the apertures, the orifice insertscomprising a body having an orifice passage way extending longitudinallytherethrough, a depending thin walled tubular member at one end of thebody through which the passageway runs axially, means on the other endof the body to attach the orifice insert to the aperture, and anenlarged passageway area open to the nozzle and extending inwardly fromthe end of the orifice insert attached to the aperture and terminatingbefore the passageway enters the thin walled tubular member at the otherend of the body,

a hot chamber housing defining a hot chamber,

said nozzle being mounted at the top of the hot chamber for sprayingliquid material through the orifice inserts directly into the hotchamber, and

heating means placed about the hot chamber to pro vide heat to the hotchamber to keep the temperature of the sprayed material from beinglowered until after it breaks up and forms droplets or prills.

5. Apparatus for prilling material, comprising:

a prilling tower with a hot chamber housing defining a hot chamber atthe top of the tower,

a nozzle having walls surrounding a pressure chamber with apertures inthe bottom wall,

removable orifice inserts in the apertures,

said nozzle being mounted at the top of the hot chamher for sprayingliquid material through the orifice inserts directly into the hotchamber, and

heating means placed about the hot chamber to provide its heatessentially only to the hot chamber and supply all the heat needed toheat the hot chamber to keep the temperature of the sprayed materialfrom being lowered until after it breaks up and forms droplets orprills.

6. Apparatus according to claim 5 in which the hot chamber isapproximately three feet in height and of sufficient width toaccommodate ,a plurality of nozzles.

References Cited UNITED STATES PATENTS 1,951,790 3/1934 Curran 182.7 X2,341,555 2/1944 Jones 18-8 2,887,724 5/1959 Bettes 182.7 X 2,931,0674/1960 Delaloye et a1.

2,968,833 1/1961 DeHaven et al. 2649' 3,048,887 8/1962 Weiland 18-2.7 X3,130,225 4/1964 Friend 18-2.7 X

WILLIAM J. STEPHENSON, Primary Examiner.

5. APPARATUS FOR PRILLING MATERIAL, COMPRISING:
 5. APPARATUS FORPRILLING MATERIAL, COMPRISING: A PRILLING TOWER WITH A HOT CHAMBERHOUSING DEFINING A PRILLING TOWER WITH A HOT CHAMBER HOUSING DEFINING AHOT CHAMBER AT THE TOP OF THE COVER. A HOT CHAMBER AT THE TOP OF THETOWER.